JP2000171539A - Magnetism detecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a magnetism detecting apparatus by which the edge accuracy of an uneven part on a magnetic rotating body can be enhanced by suppressing a change in a bias magnetic field which is applied to a magnetoresistance element. SOLUTION: A magnetic-body guide 4 is installed at the end part, to a magnetic rotating body 1, of a magnet 3 which is arranged so as to face the magnetic rotating body 1. The magnetization direction of the magnet 3 is set in a direction which faces the magnetic rotating body 1. A magnetoresistance segment 2a is arranged between the magnetic-body guide 4 and the magnetic rotating body 1 so as to be parallel with the magnetization direction. A change, in a bias magnetic field to a magnetoresistance element 2, due to the dislocation in the opposite direction of the magnetic rotating body 1 is suppressed when the magnet 3 is assembled to the magnetoresistance element 2. An irregularity in the differential amplification output of a change in the resistance, of the magnetoresistance element 4, which is voltage-converted is suppressed. As a result, the edge accuracy of an uneven part on the magnetic rotating body can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a magnetic detector,
In particular, the present invention relates to a rotation detecting device for detecting unevenness of a magnetic rotating body.

[0002]

2. Description of the Related Art Normally, a bridge is formed by forming electrodes at each end of a magneto-sensitive surface of a magnetoresistive element in order to detect a change in a magnetic field, and a constant voltage is applied between two opposing electrodes of the bridge.
There is a method of connecting a constant-current power supply, converting a change in resistance of the magnetic detection element into a change in voltage, and detecting a change in a magnetic field acting on the magnetic detection element.

FIG. 19 is a circuit diagram for processing the output of a sensor using the above-described general magnetoresistive element. As shown in the figure, a constant voltage is applied to a bridge circuit composed of a magnetoresistive element and a fixed resistor, and a change in a resistance value of the magnetoresistive element due to a change in a magnetic field is converted into a voltage change. This voltage-changed signal is amplified by the differential amplifier circuit 12, and the AC-coupled circuit 1
At 3, the DC component is removed and input to the comparison circuit 14. The signal compared with the predetermined voltage by the comparison circuit 14 is converted into a final output of “0” or “1” by the output circuit 15 and taken out to the output terminal.

FIG. 20 is a structural view showing a conventional magnetism detecting device. FIG. 20 (a) is a side view, FIG. 20 (b) is a perspective view, and FIG. 20 (c) is a top view. . In the figure, reference numeral 21 denotes a magnetic rotating body having a shape that changes the magnetic field, that is, a magnetic rotating body having irregularities, 22 denotes a magnetic resistance element, 22a denotes a magnetic resistance segment, 23 denotes a magnet, and 24 denotes a rotating shaft, and the rotating shaft 24 rotates. Thus, the magnetic rotating body 21 also rotates in synchronization. Further, the magnetic field applied to the magnetoresistive segment 22a of the magnetoresistive element 22 changes as the magnetic rotator 21 rotates, and for example, the differential of the magnetoresistive element corresponds to the shape of the magnetic rotator 21 as shown in FIG. The amplification output changes, and FIG.
The final output signal "1" or "0" corresponding to the shape of the magnetic rotating body 21 can be obtained by the processing circuit shown in FIG.

[0005]

In the above-described conventional magnetic detecting device, however, the bias magnetic field applied to the magneto-resistive element 22 is varied due to the variation in positional accuracy when the magneto-resistive element 22 and the magnet 23 are assembled. , Magnetic rotating body 2
Similarly, a variation is given to the magnetic field change to the magnetoresistive element due to the unevenness of FIG. 1, resulting in the variation of the differential amplification output Vp-p as shown by the thick solid line and the thin solid line in FIG. There has been a problem that the edge detection accuracy of the unevenness of the body 21 varies.

Further, as shown in FIG. 23, an offset occurs in the output before differential amplification output alternating current (AC) coupling due to the temperature coefficient difference between the magnetoresistive element and the fixed resistor constituting the bridge circuit. In the processing circuit, it is necessary to suppress the amplification factor of the differential amplifier circuit 12, and therefore, there is a problem that after the AC coupling, it is necessary to further add and amplify the differential amplifier circuit.

Here, with reference to FIGS. 24 and 25, a change in the bias applied magnetic field to the magnetoresistive element due to the displacement of the magnetoresistive element 22 and the magnet 23 in the direction facing the magnetic rotating body 21 is described. Will be described. FIG.
FIG. 24 shows a change in a magnetic field applied to a magnetoresistive element due to a magnet position shift in a conventional magnetic detection device.
FIG. 24A shows a case where there is no magnet position shift, and FIG.
Indicates the case where there is a magnet position shift. As shown in the figure, the bias applied magnetic field (thick arrow) to the magnetoresistive element changes due to the positional shift of the magnet 23 in the facing direction. When the magnetic rotator 21 rotates, the magnetic field applied to the magnetoresistive element 22 changes from a bias magnetic field indicated by a thick arrow to a magnetic field indicated by a thin arrow due to a change from a concave portion to a convex portion provided in the magnetic rotator 21. FIG. 25 shows a characteristic of resistance change with respect to a magnetic field applied to the magnetoresistive element (hereinafter referred to as an MR loop characteristic),
24A and 24B show the relationship between the change in the magnetic field applied to the magnetoresistive element and the change in resistance.

As shown in FIG. 25, since the change in the resistance of the magnetoresistive element is reduced due to the displacement of the magnet 23 in the facing direction, the output of the differential amplifier circuit 12 varies in the processing circuit shown in FIG. As shown in FIG. 22, variations occur in the edge detection accuracy of the unevenness of the magnetic rotating body 21.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and it is possible to improve the edge accuracy by suppressing a change in a bias magnetic field applied to a magnetoresistive element, and to improve the temperature characteristics of the magnetoresistive element. It is an object of the present invention to provide a magnetic detector capable of performing temperature compensation and simplifying a processing circuit.

[0010]

According to a first aspect of the present invention, there is provided a magnetic detecting device, comprising: a detecting section including a magnetoresistive element including at least one magnetoresistive segment for detecting an applied magnetic field intensity; , A magnetic rotator disposed opposite to the magnet and having irregularities for changing the magnetic field applied to the magnet, and a magnetic member provided at an end of the magnet near the magnetic rotator With a guide.

According to a second aspect of the present invention, in the magnetic detection device according to the first aspect of the present invention, the magnetizing direction of the magnet is set to a direction facing the magnetic rotating body, and the magnet is parallel to the magnetizing direction, and The magnetic resistance segment is arranged between the magnetic rotating bodies.

According to a third aspect of the present invention, in the magnetic detecting device according to the first or second aspect, the magnetoresistive segment is disposed with respect to the magnet with a predetermined gap in a direction of a center axis of the magnetic rotating body. Things.

According to a fourth aspect of the present invention, in the magnetic detecting device according to the third aspect of the present invention, the size of the magnetic rotating body in the rotating direction of the magnetic body guide is larger than the width of the magnet.

According to a fifth aspect of the present invention, in the magnetic detecting device according to the third aspect of the present invention, a GMR device is used as the magnetoresistive element.
An element is used.

According to a sixth aspect of the present invention, in the magnetic detecting device according to the third aspect of the present invention, at least one of the plurality of magnetoresistive segments is substantially equal to an end of the magnet of the magnetic body guide. They are arranged identically and used for temperature compensation.

According to a seventh aspect of the present invention, in the magnetic detection device according to the sixth aspect of the present invention, a half bridge circuit or a full bridge circuit is constituted by the magnetoresistive element including the plurality of segments.

According to an eighth aspect of the present invention, in the magnetic detecting device according to the fifth aspect, the magnetoresistive pattern of the magnetoresistive segment for detecting a change in the magnetic field is perpendicular to the facing direction.

According to a ninth aspect of the present invention, in the magnetic detecting device according to the fifth aspect of the present invention, a magnetoresistive pattern of a magnetoresistive segment used for temperature compensation is set in the facing direction.

According to a tenth aspect of the present invention, there is provided a magnetic detection device comprising:
In the invention according to claim 5, a magnetoresistive pattern of a magnetoresistive segment for detecting a magnetic field change is perpendicular to the facing direction, and a magnetoresistive pattern of a magnetoresistive segment used for temperature compensation is the facing direction. .

According to the eleventh aspect of the present invention, there is provided a magnetic detection device comprising:
In the invention according to claim 3, the magnetizing direction of the magnet is the facing direction, and the plurality of magnetoresistive segments are parallel to the magnetizing direction and away from the magnetic body guide in a central axis direction of the magnetic rotating body. They are arranged side by side in the magnetic body rotation direction.

According to a twelfth aspect of the present invention, there is provided a magnetic detection device comprising:
According to the eleventh aspect of the present invention, a half-bridge circuit or a full-bridge circuit is constituted by the plurality of magnetoresistance segments arranged in parallel.

According to a thirteenth aspect of the present invention, there is provided a magnetic detection device comprising:
In the eleventh aspect, the plurality of magnetoresistive segments arranged in parallel have a magnetoresistive pattern in the facing direction.

According to a fourteenth aspect of the present invention, there is provided a magnetic detection device comprising:
In the eleventh aspect, the pitch of the magnetoresistive segments arranged in parallel to the rotation direction of the magnetic rotator is 1.2 to 1.8 mm.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings. Embodiment 1 FIG. FIG. 1 shows a configuration diagram of the first embodiment. FIG. 1A is a side view, FIG. 1B is a perspective view, and FIG. 1C is a top view. In the figure, a magnetic rotator 1 is provided with irregularities for changing a magnetic field applied to a magnetoresistive element 2 constituting a detection unit, and rotates in synchronization with a rotating shaft 5. The magnet 3 is disposed so as to face the magnetic rotating body 1 and is magnetized in the facing direction. The magnetic body guide 4 is arranged at the end of the magnet 3 near the magnetic rotating body 1. The magnetoresistive element 2 is an in-plane magnetoresistive element composed of one or more segments, and is parallel to the magnetizing direction of the magnet 3. It is arranged between the magnetic body guide 4 and the magnetic rotating body 1.
The magnetoresistive segment 2a is a segment of the magnetoresistive element 2. Note that the configuration and operation principle of the processing circuit according to the present embodiment are substantially the same as those in FIGS. 19 and 21 described above, and a description thereof will be omitted.

Next, a description will be given of a change in a magnetic field applied to the magnetoresistive element 2 due to a positional shift between the magnetoresistive element 2 and the magnet 3 in a direction facing the magnetic rotator 1. FIG. FIG.
FIG. 2A shows a change in a bias applied magnetic field to the magnetoresistive element due to the displacement of the magnet 3 in the facing direction in the present embodiment. FIG. 2A shows a case where the magnet 3 has no displacement.
FIG. 2B shows a case where the magnet 3 is misaligned.

As shown in the figure, the bias applied magnetic field (thick arrow) to the magnetoresistive element 2 changes due to the displacement of the magnet 3. When the magnetic rotator 1 rotates, the magnetic field applied to the magnetoresistive element 2 changes from a bias magnetic field indicated by a thick arrow to a magnetic field indicated by a thin arrow due to a change from a concave portion to a convex portion provided in the magnetic rotator 1.

FIG. 3 shows the relationship between the MR loop characteristics of the magnetoresistive element and the change in the magnetic field applied to the magnetoresistive element and the change in resistance in the cases of FIGS. 2 (a) and 2 (b). As shown in the figure, there is no change in the resistance of the magnetoresistive element 2 due to the displacement of the magnet 3 in the facing direction, and there is no variation in the output of the differential amplifier circuit 12 in the processing circuit (FIG. 19). Since unevenness in the edge detection accuracy of the unevenness of the magnetic rotating body can be suppressed, the edge accuracy of the unevenness of the magnetic rotating body can be improved.

As described above, in the present embodiment, the magnetic body guide is provided at the end of the magnet rotating body opposed to the magnetic rotating body, and the magnetizing direction is set to the direction facing the magnetic rotating body. By disposing the magnetoresistive segment parallel to the magnetization direction and between the magnetic body guide and the magnetic rotator, the magnet and the magnetic rotator can be moved to the magnetoresistive element due to misalignment in the facing direction when the magnet and the magnetoresistive element are assembled. To suppress the variation of the bias magnetic field, and the variation of the differential amplification output of the resistance change of the voltage-converted magnetoresistive element, thereby improving the edge accuracy of the concave and convex portions of the magnetic rotating body.

Embodiment 2 This embodiment is different from the first embodiment in the configuration of FIG.
This is to optimize the distance L in the rotation axis direction from the magnet 3 having the magnetic material guide 4 disposed at the end. For example, it is assumed that the MR loop characteristic of the magnetoresistive element 2 is the characteristic shown in FIG. In this case, the rotation axis distance L between the magnetoresistive element 2 and the magnet 3 may be optimized so that the bias magnetic field applied to the magnetoresistive element 2 is about 15 [kA / m]. For example, specifically giving numerical values, the configuration shown in FIG. 5 allows the bias magnetic field applied to the magnetoresistive element 2 to be set to around 15 [kA / m], which is the highest sensitivity.
Since the change in the bias magnetic field due to the displacement of the magnet 3 in the facing direction can also be suppressed, the noise immunity can be increased and the edge accuracy can be improved by improving the SN ratio.

By the way, although this numerical value is based on an experiment, the size of the magnet 3 is such that the size (magnet width) in the rotation direction of the magnetic rotating body 1 is 5 mm, the size in the axial direction is 3 mm, and the size in the magnetization direction (thickness). ) Is 5 mm, the size of the magnetic body guide 4 is 10 mm in the rotation direction of the magnetic rotating body 1, 3 mm in the axial direction, 1.6 mm in the magnetization direction (thickness), and the magnetic resistance element 2 The distance from the center of the magnetic material guide 4 to the end of the magnetic material guide 4 is 1.7 mm.

As described above, in the present embodiment, the magnetoresistive element is arranged with respect to the magnet with a predetermined gap in the direction of the center axis of the magnetic rotating body, so that the most sensitive applied magnetic field range of the magnetoresistive element is obtained. , And the noise immunity can be increased by improving the SN ratio.

Embodiment 3 FIG. This embodiment relates to the size of the rotation direction size M of the magnetic rotating body 1 of the magnetic body guide 4 in the configuration of FIG. 1 in the first embodiment, and as shown in FIG. By making the magnetism larger, the magnetic field component in the facing direction does not change even if the position of the magnet 3 in the rotational direction shifts, so that the magnetoresistive element 2
Changes in the bias magnetic field applied to the
Edge accuracy can be improved.

As described above, in the present embodiment, the size of the magnetic rotating body in the rotating direction is made larger than the magnet width,
Variations in the bias magnetic field applied to the magnetoresistive element due to misalignment of the magnetic rotating body in the rotational direction when the magnet and the magnetoresistive element are assembled can be suppressed. Therefore, the edge accuracy of the unevenness of the magnetic rotating body can be improved.

Embodiment 4 In the present embodiment, a giant magnetoresistive element (hereinafter, referred to as a GMR element) is used as the magnetic sensing element 2. Note that the configuration and the processing circuit in this case may be the same as those in the first embodiment. GMR element, Journal of the Japan Society of Applied Magnetics Vol.15, No.5199
1, p813 ~ 821 It is a so-called artificial lattice film in which magnetic layers and non-magnetic layers each having a thickness of several angstroms to several tens angstroms described in the magnetoresistance effect of the artificial lattice are alternately laminated, Fe / Cr) n, (Permalloy / Cu / Co / Cu) n, and (Co / Cu) n (n is the number of layers) are known, which are commonly used magnetoresistive elements (hereinafter referred to as MR elements). Has a much larger MR effect (MR change rate) than that of the magnetic layer, and depends only on the relative angle of the magnetization directions of the adjacent magnetic layers. This is an in-plane magneto-sensitive element that can obtain the same change in resistance value even if it has. However, it is also an element that can provide anisotropy by reducing the width of the magnetoresistive pattern.

The GMR element has a characteristic that a resistance value change due to a change in an applied magnetic field has a hysteresis and a temperature characteristic, particularly a large temperature coefficient. FIG. 7 shows the MR loop characteristics of this GMR element.

As described above, in this embodiment, the SN ratio is improved by using the GMR element in particular for the magnetoresistive element.
Noise tolerance can be improved.

Embodiment 5 FIG. 8 is a configuration diagram of a magnetic circuit according to the present embodiment, and FIG.
8B is a perspective view, and FIG. 8C is a top view thereof. In the figure, the magnetoresistive segment 32b of the magnetoresistive element 32
Are arranged substantially the same as the end of the magnetic material guide 34 near the magnet 33 for temperature compensation. The configurations of the magnetic rotator 31, the magnetic resistance segment 32a of the magnetic resistance element 32, the magnet 33, and the magnetic material guide 34 are as follows. This is the same as the magnetic circuit configuration of the first and second embodiments (FIG. 1), and a detailed description thereof will be omitted.

FIG. 9 shows a configuration of a processing circuit according to the fifth embodiment. A magnetoresistive segment 32b is connected between an inverting input terminal and an output terminal of an amplifier 42a of a differential amplifier circuit 42, and this is used for temperature compensation. Except for the use, the configuration is the same as that of the processing circuit in FIG. The differential amplifier circuit 42 increases its gain because the resistance value of the magnetoresistive segment 32b increases as the temperature increases, and conversely decreases the resistance value of the magnetoresistive segment 32b as the temperature decreases. The magnetoresistive segment 32 MR change rate temperature characteristic (the MR change rate decreases as the temperature increases,
When the temperature decreases, the MR change rate increases), and the output always functions within the desired amplitude range without being affected by the temperature.

Therefore, by using the magnetoresistive segment 32b for temperature compensation, the MR of the magnetoresistive segment 32a constituting the bridge in the processing circuit of FIG.
The output amplitude temperature characteristic of the differential amplifier circuit 42 due to the change rate temperature characteristic can be compensated, and the edge accuracy temperature characteristic can be improved.

As described above, in the present embodiment, at least one of the plurality of magnetoresistive segments is arranged substantially identical to the end of the magnet of the magnetic material guide,
By using the magnetic rotor for temperature compensation, the temperature characteristics of the edge accuracy of the magnetic rotating body unevenness can be improved.

Embodiment 6 FIG. The configuration of the sixth embodiment is the same as that of the fifth embodiment, and a description thereof will be omitted. FIG. 10 shows a configuration of a processing circuit according to the sixth embodiment. The configuration is the same as that of the processing circuit of FIG. 1 except that a bridge circuit is configured by the magnetoresistive segments 32a and 32b. I do.

In the figure, the magnetoresistive segments 32a,
32b, the temperature offset of the midpoint output of the bridge circuit is suppressed, and the differential amplifier circuit 4
2 can be increased, and amplification after AC coupling is not required, so that cost can be reduced by simplifying the processing circuit.

As described above, in the present embodiment, the half-bridge circuit or the full-bridge circuit is used for the magnetoresistive segment to which the magnetic field change corresponding to the magnetic rotator unevenness is applied and the magnetoresistive segment used for temperature compensation. By suppressing the temperature offset of the midpoint output of the bridge circuit, the amplification factor of the differential amplifier circuit can be increased,
Since amplification after AC coupling is not required, cost can be reduced by simplifying the processing circuit.

Embodiment 7 FIG. The seventh embodiment relates to a magnetoresistive pattern when the GMR element used in the fourth embodiment is applied to the magnetoresistive element 2 in the first embodiment. First, FIG. 11 shows the MR loop characteristics when the magnetoresistive pattern of the magnetoresistive element 2 using the GMR element is formed in a direction facing the magnetic rotator 1 and when the magnetoresistive pattern is formed perpendicular to the facing direction.

As shown in the figure, when the pattern is formed in the vertical direction indicated by the solid line, the hysteresis is smaller and the operating magnetic field range is larger than when the pattern is formed in the opposite direction indicated by the broken line. By setting the magnetoresistive pattern of the magnetoresistive element used in Step 1 in the vertical direction, it is possible to further suppress the amplitude change of the differential amplifier circuit output due to the positional deviation of the magnet described in Embodiment 1 and to reduce the edge accuracy. Can be improved.

As described above, in the present embodiment, the magnetic resistance pattern of the magnetoresistive segment to which the magnetic field change corresponding to the unevenness of the magnetic rotating body is applied is made perpendicular to the direction facing the magnetic rotating body, so that the magnet The change in the amplitude of the output of the differential amplifier circuit due to the displacement can be suppressed, and the edge accuracy can be improved.

Embodiment 8 FIG. The eighth embodiment relates to the magnetoresistive pattern of the magnetoresistive segment 32b used for temperature compensation in the fifth embodiment. Magnetoresistive segment 3 used for temperature compensation
2b is desirably used in an applied magnetic field in which the resistance value is substantially saturated from the viewpoint of the bridge output stability in the MR loop characteristic of FIG. 11, and the magnetoresistive pattern in the facing direction can be used in a more saturated region. , Accurate temperature compensation is possible, and the edge accuracy can be improved.

As described above, in the present embodiment, by setting the magnetoresistive pattern of the magnetoresistive segment used for temperature compensation in the facing direction, the resistance value variation due to a positional shift when the magnetoresistive element and the magnet are assembled. And the edge accuracy of the magnetic rotating body irregularities can be improved.

Embodiment 9 FIG. The ninth embodiment relates to a magnetoresistive pattern of the magnetoresistive segment 32a used for detecting a magnetic field change and the magnetoresistive segment 32b used for temperature compensation in the sixth embodiment. The magnetoresistive pattern of the magnetoresistive segment 32a used for detecting the change in the magnetic field is the vertical direction described in the seventh embodiment, and the magnetoresistive pattern of the magnetoresistive segment 32b used for the temperature compensation is the opposite direction described in the eighth embodiment. By using the directional pattern, a change in amplitude of the output of the differential amplifier circuit due to a positional shift between the magnet and the magnetoresistive element can be suppressed and large, accurate temperature compensation can be performed, and edge accuracy can be improved.

As described above, in this embodiment, the magnetoresistive pattern of the magnetoresistive segment used for detecting a magnetic field change is formed perpendicular to the direction facing the magnetic rotating body, and the magnetic resistance of the magnetoresistive segment used for temperature compensation is changed. By setting the resistance pattern in the opposite direction, a change in the amplitude of the output of the differential amplifier circuit due to a positional shift between the magnet and the magnetoresistive element is suppressed,
Accurate temperature compensation becomes possible, and the edge accuracy can be improved.

Tenth Embodiment FIG. 12 is a block diagram of a tenth embodiment, in which FIG.
12B is a side view, FIG. 12B is a perspective view thereof, and FIG.
(C) is a top view thereof. In the figure, the magnetic rotor 5
Numeral 1 is provided with irregularities for changing the magnetic field applied to the magnetoresistive element 52, and rotates in synchronization with the rotating shaft 55. The magnet 53 is disposed so as to face the magnetic rotating body 51 and is magnetized in the facing direction. The guide 54 is a magnet 5
3, a magneto-resistive element 52 is an in-plane magneto-sensitive element composed of two or more magneto-resistive segments 52a, 52b, and is parallel to the magnetization direction and has a magnetic guide. It is arranged between 54 and the magnetic rotating body 51.

FIG. 13 shows a configuration of a processing circuit according to the tenth embodiment. Except for the magnetoresistive segments 52a and 52b constituting the half bridge, the configuration is the same as that of the processing circuit of FIG. 1, and the description thereof is omitted. FIG. 14 shows operation waveforms of the tenth embodiment. As the magnetic rotating body 51 rotates, the magnetic field applied to the magnetoresistive segments 52a and 52b of the magnetoresistive element 52 changes, and as shown in FIG. The resistance of the magnetoresistive segments 52a and 52b changes, and the output of the differential amplifier circuit 56 changes. The output of the differential amplifier circuit 56 is AC-coupled and D
After removing the C component, the waveform is shaped by the comparison circuit 58,
A final output signal "1" or "0" corresponding to the shape of the magnetic rotator 51 is obtained at the output terminal.

Here, as in the first embodiment, the amplitude variation of the output of the differential amplifier circuit due to the magnet position shift is suppressed to improve the edge accuracy. In particular, the magnetic rotor has a very small uneven pitch (high resolution). Effective for edge detection of (type).

As described above, in the present embodiment, the magnetizing direction of the magnet is the opposite direction, and the plurality of magnetoresistive segments are parallel to the magnetizing direction and away from the magnetic body guide in the direction of the axis of the magnetic rotating body. Are arranged side by side in parallel with the rotation direction of the magnetic body, an accurate signal corresponding to the unevenness can be obtained even in a high-resolution type magnetic rotator having a narrow magnetic rotator uneven pitch.

Embodiment 11 FIG. In the eleventh embodiment, the magnetoresistive element in the tenth embodiment has a full bridge configuration. FIG. 15 is a configuration diagram of the eleventh embodiment, and is the same as the configuration diagram of the tenth embodiment except for the magnetoresistive segments 52c and 52d. FIG. 16 shows the configuration of the processing circuit according to the eleventh embodiment. Magnetoresistance segment 52 of magnetoresistance element 52
a, 52b, 52c, and 52d constitute a full bridge and differentially amplify both midpoint outputs. Subsequent processing is the same as in the tenth embodiment, and the processing waveform is the same as in FIG. I do. Here, by adopting the configuration of the full bridge, the SN ratio can be improved, and the noise immunity can be improved.

As described above, in the present embodiment, the half-bridge circuit or the full-bridge circuit is constituted by a plurality of magnetoresistive segments arranged in parallel, so that the temperature characteristics and the SN ratio are improved. In addition, it is possible to improve the temperature characteristics of the edge accuracy of the unevenness of the magnetic rotating body and the noise immunity.

Twelfth Embodiment A twelfth embodiment relates to the magnetoresistance pattern of the magnetoresistance element 52 used in the tenth embodiment, and has the same magnetoresistance pattern as that of the seventh embodiment, that is, the magnetoresistance pattern shown in FIG. The magnetic resistance pattern of the element 52 is
A similar effect can be obtained in a case where the structure is perpendicular to the direction opposite to 1.

As described above, in the present embodiment, the magnetoresistive patterns of a plurality of magnetoresistive segments arranged in parallel are made perpendicular to the direction facing the magnetic rotating body, so that the position of the magnet is shifted. The change in the amplitude of the output of the differential amplifier circuit can be suppressed, and the edge accuracy can be improved.

Embodiment 13 The embodiment 13 relates to the pitch of the magnetoresistive segments 52a and 52b of the magnetoresistive element 52 used in the tenth embodiment. FIG. 17 is a configuration diagram of the thirteenth embodiment, in which the detailed dimensions are substantially described in the magnetic circuit configuration of the tenth embodiment. In the figure, the experimental result of confirming the output amplitude of the differential amplifier circuit in combination with the magnetic rotator 51 having the tooth width H (the same width as the concavities and convexities) and the magnetic resistance element having the pitch of the magnetic resistance segments 52a and 52b being P is shown in FIG. Shown in As shown, regardless of the tooth width H of the magnetic rotating body 51, the magnetoresistive element 5
When the pitch P of the second magnetoresistive segments 52a and 52b is about 1.4 mm, the output amplitude of the differential amplifier circuit becomes maximum, the SN ratio can be improved, and the noise immunity can be improved.

As described above, in the present embodiment, the pitch of the magnetoresistive patterns of a plurality of magnetoresistive segments arranged in parallel is set to 1.2 to 1.8 mm.
The SN ratio can be improved, and the noise tolerance can be improved.

[0061]

As described above, according to the present invention, a detecting section comprising a magnetoresistive element comprising at least one magnetoresistive segment for detecting an applied magnetic field strength, and applying a magnetic field to the magnetoresistive element. A magnet, a magnetic rotator disposed opposite to the magnet and having irregularities for changing a magnetic field applied to the magnet, and a magnetic guide provided at an end of the magnet closer to the magnetic rotator. Therefore, there is an effect that the change in the bias magnetic field applied to the magnetoresistive element is suppressed, and the edge accuracy of the unevenness of the magnetic rotating body can be improved.

Further, according to the present invention, the magnetizing direction of the magnet is set to a direction facing the magnetic rotating body, and the magnetic resistance segment is parallel to the magnetizing direction and between the magnetic body guide and the magnetic rotating body. , The change of the bias magnetic field to the magnetoresistive element due to the misalignment of the magnetic rotator in the facing direction when assembling the magnet and the magnetoresistive element,
This has the effect of suppressing the variation in the differential amplification output of the resistance change of the voltage-converted magnetoresistive element and improving the edge precision of the magnetic rotating body irregularities.

Further, according to the present invention, the magnetoresistive segment is arranged with respect to the magnet with a predetermined gap in the direction of the center axis of the magnetic rotator. And the noise immunity can be increased by improving the SN ratio.

According to the invention, the size of the magnetic rotating body in the rotating direction of the magnetic body guide is made larger than the width of the magnet, so that the rotating direction of the magnetic rotating body when assembling the magnet and the magnetoresistive element is improved. It is possible to suppress the change of the bias magnetic field to the magnetoresistive element due to the positional deviation, and to suppress the variation of the differential amplification output of the resistance change of the voltage-converted magnetoresistive element. effective.

Further, according to the present invention, since the GMR element is particularly used for the magnetoresistive element, there is an effect that the SN ratio can be improved and the noise immunity can be increased.

Further, according to the present invention, at least one of the plurality of magnetoresistive segments is arranged substantially identical to the end of the magnet of the magnetic material guide and used for temperature compensation. This has the effect of improving the temperature characteristics of the edge accuracy of the magnetic rotating body irregularities.

Further, according to the present invention, since a half-bridge circuit or a full-bridge circuit is constituted by the magnetoresistive element comprising the plurality of segments, the temperature offset of the midpoint output of the bridge circuit is suppressed, and the differential amplifier circuit is provided. Since the amplification factor can be increased and amplification after AC coupling is not required, there is an effect that the cost can be reduced by simplifying the processing circuit.

Further, according to the present invention, since the magnetoresistive pattern of the magnetoresistive segment for detecting a change in the magnetic field is perpendicular to the facing direction, a change in the amplitude of the output of the differential amplifier circuit due to a positional shift of the magnet is suppressed. Therefore, there is an effect that the edge accuracy can be improved.

Further, according to the present invention, since the magnetoresistive pattern of the magnetoresistive segment used for temperature compensation is set in the facing direction, the resistance value variation due to a positional shift when the magnetoresistive element and the magnet are assembled is eliminated. There is an effect that the edge accuracy of the magnetic rotator unevenness can be improved.

Further, according to the present invention, the magnetoresistive pattern of the magnetoresistive segment for detecting a change in the magnetic field is perpendicular to the facing direction, and the magnetoresistive pattern of the magnetoresistive segment used for temperature compensation is different from the facing direction. Therefore, there is an effect that an amplitude change of the output of the differential amplifier circuit due to a misalignment between the magnet and the magnetoresistive element is suppressed, accurate temperature compensation can be performed, and edge accuracy can be improved.

According to the present invention, the magnetizing direction of the magnet is set to the facing direction, and a plurality of magnets are arranged parallel to the magnetizing direction and away from the magnetic body guide in the direction of the center axis of the magnetic rotating body. Since the resistance segments are arranged side by side in the rotation direction of the magnetic body, there is an effect that an accurate signal corresponding to the unevenness can be obtained even in a high resolution type magnetic rotating body having a narrow magnetic unevenness pitch.

Further, according to the present invention, since the half-bridge circuit or the full-bridge circuit is constituted by the plurality of magnetoresistive segments arranged in parallel, the temperature characteristics and the SN ratio are improved, and the magnetic rotator is improved. This has the effect of improving the temperature characteristics of the edge accuracy of the irregularities and increasing the noise resistance.

According to the present invention, the magnetoresistive pattern of the plurality of magnetoresistive segments arranged in parallel is perpendicular to the direction facing the magnetic rotating body, so that the difference due to the misalignment of the magnets. There is an effect that the amplitude change of the output of the dynamic amplifier circuit can be suppressed, and the edge accuracy can be improved.

Further, according to the present invention, the pitch of the magnetoresistive segments arranged in parallel to the rotation direction of the magnetic rotator is set to 1.2 to 1.8 mm, so that the SN ratio is improved and the noise resistance is improved. There is an effect that can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a change in a magnetic field vector according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating an MR loop characteristic of a magnetoresistive element and a resistance change region according to the first embodiment.

FIG. 4 is a diagram showing an MR loop characteristic of a magnetoresistive element and a resistance change optimum applied magnetic field region.

FIG. 5 is a configuration diagram showing a second embodiment of the present invention.

FIG. 6 is a magnetic field vector diagram according to the third embodiment of the present invention.

FIG. 7 is an MR loop characteristic diagram of the GMR element.

FIG. 8 is a configuration diagram showing a fifth embodiment of the present invention.

FIG. 9 is a diagram showing a processing circuit according to a fifth embodiment of the present invention.

FIG. 10 is a diagram showing a processing circuit according to a sixth embodiment of the present invention.

FIG. 11 is an MR loop characteristic diagram according to a magnetoresistive pattern configuration of a GMR element.

FIG. 12 is a configuration diagram showing a tenth embodiment of the present invention.

FIG. 13 is a diagram illustrating a processing circuit according to a tenth embodiment of the present invention.

FIG. 14 is a diagram showing output signals according to the tenth embodiment of the present invention.

FIG. 15 is a configuration diagram showing an eleventh embodiment of the present invention.

FIG. 16 is a diagram showing a processing circuit according to an eleventh embodiment of the present invention.

FIG. 17 is a configuration diagram showing a thirteenth embodiment of the present invention.

FIG. 18 is a diagram illustrating an output amplitude of a differential amplifier circuit according to Embodiment 13 of the present invention.

FIG. 19 is a diagram showing a processing circuit in a conventional magnetic detection device.

FIG. 20 is a configuration diagram showing a conventional magnetic detection device.

FIG. 21 is a diagram showing an output signal in a conventional magnetic detection device.

FIG. 22 is a diagram showing an output signal in a conventional magnetic detection device.

FIG. 23 is a diagram showing an output signal in a conventional magnetic detection device.

FIG. 24 is a diagram showing a change in a magnetic field vector in a conventional magnetic detection device.

FIG. 25 is a diagram showing an MR loop characteristic of a magnetoresistive element and a resistance change region in a conventional magnetic detection device.

[Explanation of symbols]

1,31,51 magnetic rotator, 2,32,52 magnetoresistive element, 2a, 32a, 32b, 52a, 52b, 52c,
52d magnetoresistive segment, 3,33,53 magnet, 4,34,54 magnetic material guide, 12,42,
56 differential amplifier circuit, 13, 43, 57 AC coupling circuit, 14, 44, 58 comparison circuit, 15, 45, 5
9 Output circuit.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takuji Nada 2-3-2 Marunouchi, Chiyoda-ku, Tokyo F-term in Mitsubishi Electric Corporation (reference) 2G017 AA02 AB05 AB09 AC04 AC09 AD55 AD63 AD65 BA09 BA10

Claims (14)

[Claims] A detecting unit configured to detect a magnitude of an applied magnetic field, the detecting unit including a magnetoresistive element including at least one magnetoresistive segment; a magnet configured to apply a magnetic field to the magnetoresistive element; A magnetic detection device, comprising: a magnetic rotator having irregularities for changing a magnetic field applied to a magnet; and a magnetic guide provided at an end of the magnet closer to the magnetic rotator. 2. A magnetizing device according to claim 1, wherein the magnetizing direction is a direction facing the magnetic rotating body, and the magnetoresistive segments are arranged in parallel with the magnetizing direction and between the magnetic body guide and the magnetic rotating body. The magnetic detection device according to claim 1, wherein 3. The magnetic detection device according to claim 1, wherein the magnetic resistance segment is arranged with a predetermined gap in a direction of a center axis of the magnetic rotating body with respect to the magnet. 4. The magnetism detecting device according to claim 3, wherein the rotation direction size of the magnetic rotating body in the magnetic body guide is larger than the width of the magnet. 5. The magnetic detecting device according to claim 3, wherein a GMR element is used as the magnetoresistive element. 6. The method according to claim 1, wherein at least one of the plurality of magnetoresistive segments of the magnetoresistive element is disposed substantially identical to an end of the magnet of the magnetic material guide and used for temperature compensation. The magnetic detecting device according to claim 3, wherein 7. The magnetic detection device according to claim 6, wherein a half-bridge circuit or a full-bridge circuit is constituted by the magnetoresistive element including the plurality of magnetoresistive segments. 8. The magnetism detecting device according to claim 5, wherein a magnetoresistive pattern of the magnetoresistive segment is perpendicular to a facing direction of the magnet and the gyromagnetic body. 9. The magnetic detecting device according to claim 5, wherein the magnetoresistive pattern of the magnetoresistive segment is set in a direction in which the magnet and the magnetic rotator face each other. 10. A magnetic sensor used for temperature compensation, wherein a magnetoresistive pattern of a magnetoresistive segment used as an element for detecting a magnetic field change is perpendicular to the facing direction among a plurality of magnetoresistive segments of the magnetoresistive element. 6. The magnetism detecting device according to claim 5, wherein a magnetoresistive pattern of the resistance segment is set in the facing direction. 11. A magnetizing direction of the magnet is defined as the facing direction, and a plurality of magnetoresistive segments are parallel to the magnetizing direction and away from the magnetic body guide in a central axis direction of the magnetic rotating body. 4. The magnetic detecting device according to claim 3, wherein the magnetic detecting device is arranged side by side in the body rotation direction. 12. The magnetic detecting device according to claim 11, wherein a half-bridge circuit or a full-bridge circuit is constituted by the plurality of magnetoresistive segments. 13. The magnetic detection device according to claim 11, wherein a magnetoresistive pattern of the magnetoresistive segment is perpendicular to the facing direction. 14. The pitch of the magnetoresistive segments arranged in parallel to the direction of rotation of the magnetic rotator is 1.2 to 1.
The magnetic detection device according to claim 11, wherein the length is 8 mm.